This invention relates to servo cylinders generally and to self-contained servo gas cylinders pre-charged with compressed working fluid for operation without external power specifically.
In the parent application it has been demonstrated vividly that the use of linear actuators energized by a working fluid under pressure in a self-contained rechargeable system that employs tubular housing as a fluid reservoir comprising of two fluid chambers separated by a piston to maintain fluid pressure therein so as to either lock piston and rod assembly in a selected axially variable position or to allow axial motion within stroke limitations permitted in order to find its own position consistent with a closed-loop servo system operation requires utilization of simple directional check valve in the cylinder charging end including metering valve means for speed control incorporated into a actuating rod means of the unit be it metal or plastic or a combination thereof. However, many applications require cost reduction beyond that identified in the construction cited even when the unit is injection molded from plastics. Further, safety consideration necessitated design modification in the original unit operating with simplified O-ring mounting without increase of production cost. Finally, broadening the application commanded other changes.